Will Pooley, from Eyke, near Woodbridge, caught the potentially deadly virus while treating patients at a hospital in Kenema, Sierra Leone.

The 29-year-old was flown back to the UK for treatment in an isolation unit at the Royal Free Hospital in north London, where he was given the first dose of the experimental drug ZMapp on Monday.

Hopes of a breakthrough in the fight against Ebola have since been raised by the 100% successful treatment of 18 rhesus macaque monkeys with ZMapp, which cured the animals even when administered five days after infection, while they were displaying severe symptoms.

The Royal Free Hospital last night said there had been no update in Mr Pooley’s condition since Wednesday, when consultant and clinical lead in infectious diseases Michael Jacobs said the volunteer health worker was receiving round-the-clock care but that his treatment could take weeks, if not longer, and that there was no guarantee he will survive.

Mr Pooley has been praised by colleagues as “particularly brave” after he risked his life to volunteer at the Kenema Government Hospital when he heard about the need for medics.

Dr Oliver Johnson, who worked with him in Sierra Leone, said he was an “extraordinary guy” who knew the risks involved but was prepared to take them for the sake of the patients.

Health chiefs have insisted the risk to the British public from Ebola “remains very low”.